Vale operating apparatus for an internal combustion engine

ABSTRACT

Valve operating apparatus is disclosed in which the valves are operated by rocker arms driven by cams having different cam profiles and hydraulically operated coupling mechanisms for selectively connecting or disconnecting adjacent rocker arms to vary the operation of the valves under different engine operating conditions. The coupling mechanisms are operated by fluid supplied through the rocker shaft mounting the rocker arms. The rocker shaft is divided into independent fluid supply passages whereby the couplings can be supplied independently with operating fluid in order to expand the number of available valve operating control modes. Variations are described in which operating fluid can be independently supplied to various ancillary hydraulically-operated equipment, as well as to the selective coupling mechanisms.

.Iadd.This application is a continuation of application Ser. No.386,716, filed Jul. 31, 1989, abandoned..Iaddend.

BACKGROUND OF THE INVENTION

The present invention relates to valve operating apparatus for aninternal combustion engine. More particularly, the invention involvesvalve operating apparatus of the type including a camshaft rotatablydriven by the engine, a plurality of cams on the camshaft for operatingthe intake or exhaust valves according to a selected mode of operation,and pivotably mounted rocker arms for opening and closing the valves inresponse to rotation of the cams.

In valve operating devices of the type described, driver rocker armsoperably connected to the valve or valves to be operated, and freerocker arms, independent of the valves, are disposed adjacent each otherand are operably in different modes by rotation of the cams. A selectivecoupling carried by the rocker arms are hydraulically actuable forselectively interconnecting or disconnecting the respective rocker armsaccording to the desired mode of valve operation.

In such valve operating device, it is general practice to selectrelative valve diameters, valve timings, and valve lifts in view of ahigh-speed range for higher engine output power. However, if an intakevalve is actuated at constant valve timing and valve lift throughout afull engine speed range from low to high speeds, then the speed of flowof an air-fuel mixture into the combustion chamber varies from enginespeed to engine speed since the amount of air-fuel mixture introducedper unit time varies from engine speed to engine speed. At low enginespeeds, the speed of flow of the air-fuel mixture is lowered, thecharging efficiency is lowered, and the air-fuel mixture is not mixedand atomized appropriately in the combustion chamber, resulting in slowcombustion therein. Therefore, no stable combustion is achieved, and theengine speed becomes irregular during the low-speed operation.Consequently, the combustion efficiency, the fuel economy, and theknocking margin lowered are all reduced.

One solution to the above problem is suggested in Japanese Laid-OpenPatent Publication No. 59-226216. According to that solution, some ofthe intake and/or exhaust valves remain closed when the engine operatesat a low speed, whereas all of the intake and exhaust valves areoperated, i.e., alternately opened and closed, during high-speedoperation of the engine. Controlling the valves differently in low- andhigh-speed ranges, as suggested by this reference, is not totallydispositive of the problem, however. For example, if the valve controlwere effected in different modes in more speed ranges, the engine outputpower would be increased, stable low-speed operation would becomepossible, and the fuel economy would be improved.

In the above-referred prior art valve operating device, moreover,hydraulic passages for supplying hydraulic pressure respectively to theselective coupling means are defined by dividing the inner space of therocker shaft by means of a steel ball that is forcibly inserted into andsecurely positioned in the rocker shaft. With such a structure, thehydraulic pressure must be supplied from the axially opposite sides ofthe rocker shaft, and hence the hydraulic pressure supply circuit forthe valve operating device for use in a multicylinder internalcombustion engine becomes complex.

It is to the amelioration of these problems, therefore, that the presentinvention is directed.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a valve operatingdevice for an internal combustion engine in which valves are controlledin a multitude of speed ranges by a simplified hydraulic pressure supplycircuit. The invention contemplates selectively actuable coupling meansdisposed between adjacent ones of the rocker arms for interconnectingand disconnecting the rocker arms. According to one particularlybeneficial embodiment, the valve operating device employs a camshafthaving three adjacent cams. Three pivotally mounted rocker arms are heldin sliding contact with the respective cams, one of the rocker armsbeing a free rocker arm and the other two being driver rocker armsoperably connected to the intake or exhaust valves for opening andclosing them. The selective coupling means between adjacent rocker armsare each independently supplied with operating fluid so that a greaternumber of engine speed ranges can be controlled.

To accomplish this, the rocker shaft is divided by axially extendingpartitions into a plurality of hydraulic pressure supply passages forseparate communication with the respective coupling means.

By separately and selective actuating the respective coupling means inaccordance with the operating conditions of the engine, the rocker armscan be operated in different modes, and the valves can be controlled ina large number of speed ranges. The required hydraulic pressure controlcircuit is simplified because the hydraulic supply passages defined inthe rocker shaft by the axially extending partitions communicateseparately with the respective coupling means.

Moreover, as a result of the provision of separate, independenthydraulic pressure supply passages, the supply of operating fluid forother than selective coupling operation can readily be accommodated. Inthis regard, the present invention also contemplates, in relatedembodiments, the independent supply of operating fluid; for example, tohydraulic lash adjusters employed between the rocker arm and theassociated valve. In addition, fluid, such as oil, for lubricatingvarious parts of the apparatus can also be provided.

For a better understanding of the invention, its operating advantagesand the specific objective obtained by its use, reference should be madeto the accompanying drawings and description which relate to a preferredembodiment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of valve operating apparatus according tothe present invention taken along line I--I of FIG. 2;

FIG. 2 is a plan view of the valve operating apparatus of FIG. 1;

FIG. 3 is a sectional view taken along line III--III of FIG. 1;

FIGS. 4, 5 and 6 are sectional views taken along line IV--IV of FIG. 1illustrating the selective coupling means in various operatingconditions;

FIGS. 7 and 8 are sectional views similar to FIG. 4 illustratingadditional embodiments of selective coupling means contemplated by theinvention;

FIG. 9 is a plan view illustrating another cam arrangement contemplatedfor use in practice of the invention;

FIG. 10 is a sectional elevational view of the valve operating apparatusof the present invention in which a hydraulic adjuster is incorporated;

FIG. 11 is a view similar to FIG. 10 illustrating the furtherincorporation of lubrication means;

FIG. 12 is a plan view of another embodiment of the present invention;

FIG. 13 is a sectional view taken along line XIII--XIII of FIG. 12;

FIG. 14 is a partial sectional view taken along line XIV--XIV of FIG.13;

FIG. 15 is a view similar to FIG. 14 illustrating another embodiment ofthe invention;

FIGS. 16 and 17 are sectional views similar to FIG. 13 illustratingstill further embodiments of the invention;

FIG. 18 is a plan view similar to FIG. 12 illustrating yet anotherembodiment of the invention; and

FIGS. 19, 20 and 21 are sectional views similar to FIG. 14, illustratingthree additional embodiments of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

In FIGS. 1 and 2, which show a first embodiment of the presentinvention, a pair of intake valves 1a, 1b are disposed in the body of aninternal combustion engine. The valves 1a, 1b can be opened and closedby a first low-speed cam 3, a second low-speed cam 4, and a high-speedcam 5 which are integrally formed on a camshaft 2 rotatable insynchronism with rotation of the engine at a speed ratio of 1/2 withrespect to the speed of rotation of the engine. The cams 3, 4, 5 operatefirst, second and third rocker arms 7, 8, 9 pivotally supported on arocker shaft 6 extending parallel to the camshaft 2.

The camshaft 2 is rotatably disposed above the engine body. Thehigh-speed cam 5 is integrally formed on the camshaft 2 in alignmentwith an intermediate position between the intake valves 1a, 1b. Thefirst low-speed cam 3 has a cam profile to meet low-speed operation ofthe engine and includes a cam lobe 3a projecting radially outwardly to arelatively small extent. The high-speed cam 5 has a cam profile to meethigh-speed operation of the engine and includes a cam lobe 5a projectingradially outwardly to a greater extent than the cam lobe 3a, the camlobe 5a also having a larger angular extent than the cam lobe 3a. Thesecond low-speed cam 4 also has a cam profile to meet the low-speedoperation of the engine and includes a cam lobe 4a projecting radiallyoutwardly to a relatively small extent, the cam lobe 4a being smallerthan the cam lobe 3a.

The rocker shaft 6 is fixed below the camshaft 2. The first throughthird rocker arms, 7 through 9, which are operated respectively by thehigh-speed cam 5, the first low-speed cam 3, and the second low-speedcam 4, are pivotally supported on the rocker shaft 6. The rocker arms 7,8, 9, have on their upper portions cam slippers 7a, 8a, 9a, held insliding contact with the cams 3, 4, 5, respectively. The second andthird rocker arms, 8, 9, extend to positions above the intake valves 1a,1b. Tappet screws 12, 13 are threaded through distal ends of the secondand third rocker arms 8, 9 and are engageable with the upper ends of theintake valves 1a, 1b.

Flanges 14, 15 are attached to the upper ends of the intake valves 1a,1b. The intake valves 1a, 1b are normally urged upward, i.e., in aclosing direction by compression coil springs 16, 17 disposed on theintake valves 1a, 1b between the flanges 14, 15 and the engine body.

As shown in FIG. 3, a cylindrical lifter 19 having a closed upper end isdisposed as a pushing means in abutment against a lower surface of theend of the first rocker arm 7. The lifter 19 is normally urged upwardlyby a lifter spring 20 of relatively weak resiliency interposed betweenthe lifter 19 and the engine body (not shown) for resiliently biasingthe cam slipper 7a of the first rocker arm 7 slidably against thehigh-speed cam 5.

As illustrated in FIG. 4 the first and second rocker arms 7, 8 aredisposed in laterally adjacent sliding contact with each other. A firstselectively actuated coupling 21 is operatively disposed between thefirst and second rocker arms 7, 8 for selectively disconnecting therocker arms 7, 8 from each other for relative angular displacement andalso for interconnecting the rocker arms 7, 8 for their movement inunison. Likewise, the first and third rocker arms 7, 9 are disposed inlaterally adjacent sliding contact with each other. A second selectivelyactuated coupling 22 is operatively disposed between the first and thirdrocker arms 7, 9 for selectively disconnecting the rocker arms 7, 9 fromeach other for relative angular displacement and also forinterconnecting the rocker arms 7, 9 for their movement in unison.

The first and second selectively actuated couplings 21, 22 are of anidentical construction, and hence only the first coupling 21 willhereinafter be described in detail. The first coupling 21 comprises apiston 23 movable between a position in which is interconnects the firstand second rocker arms 7, 8 and a position in which it disconnects thefirst and second rocker arms 7, 8 from each other. Also provided are astopper 24 for limiting the movement of the piston 23, and a spring 25for urging the stopper 24 to move the piston 23 toward the position todisconnect the first and second rocker arms 7 and 8 from each other.

The first rocker arm 7 has a first guide hole 26 opening toward thesecond rocker arm 8 and extending parallel to the rocker shaft 6. Thefirst rocker arm 7 also has a smaller-diameter hole 28 near the closedend of the first guide hole 26 with a step 27 being defined between thesmaller-diameter hole 28 and the first guide hole 26. The piston 23 isslidably fitted in the first guide hole 26. The piston 23 and the closedend of the smaller-diameter hole 28 cooperate to define therebetween ahydraulic pressure chamber 29.

The second rocker arm 8 has a second guide hole 35 opening toward thefirst rocker arm 7 for registration with the first guide hole 26 in thefirst rocker arm 7. The circular stopper 24 is slidably fitted in thesecond guide hole 35. The second rocker arm 8 also has asmaller-diameter hole 376 near the closed end of the second guide hole35 with a step 36 defined between the second guide hole 35 and thesmaller-diameter hole 37 for limiting movement of the circular stopper24. The second rocker arm 8 also has a through-hole 38 defined coaxiallywith the smaller-diameter hole 37. A guide rod 39 joined integrally andcoaxially to the circular stopper 24 extends through the hole 38. A coilspring 25 is disposed around the guide rod 39 between the stopper 24 andthe closed end of the smaller-diameter hole 37.

The piston 23 has an axial length selected such that, when one end ofthe piston 23 abuts against the step 27, the other end thereof ispositioned at the interface between the first and second rocker arms 7,8, and, when the piston 23 is moved into the second guide hole 35 untilit displaces the stopper 24 into abutment against the step 36, the saidone end of the piston 23 remains in the first guide hole 26.

The rocker shaft 6 has an axially extending partition 31 forced orfixedly mounted therein or it may be integrally formed therewith. Thepartition 31 divides the inner space of the rocker shaft 6 into twolongitudinally parallel, hydraulic pressure supply passages 32, 33.

The first rocker arm 7 has adjacent one end a hydraulic passage 34defined therein in communication with the hydraulic pressure chamber 29of the first coupling 21. The rocker shaft 6 has a hole 40 definedtherein and providing communication between the hydraulic passage 34 andthe hydraulic passage supply passage 32 irrespective of how the firstrocker arm 7 is angularly moved about the rocker shaft 6. The firstrocker arm 7 has adjacent to its other end an annular groove 41surrounding the rocker shaft 6 and a hydraulic passage 42 through whichthe annular groove 41 communicates with the hydraulic pressure chamber29 of the second coupling 22. The rocker shaft 6 has a hole 43 providingcommunication between the hydraulic pressure supply passage 33 and theannular groove 41. Therefore, the hydraulic pressure chamber 29 of thefirst coupling 21 communicates with the hydraulic pressure supplypassage 32, and the hydraulic pressure chamber 29 of the second coupling22 communicates with the hydraulic pressure supply passage 33. The firstand second couplings 21, 22 can thus be operated independently of eachother.

Operation of the valve operating mechanism is as follows. When theengine is to operate in a low-speed range, the first and secondcouplings 21, 22 are actuated to disconnect the first through thirdrocker arms 7, 8, 9 from each other as illustrated in FIG. 4. Morespecifically, hydraulic pressure is released from the hydraulic pressurechamber 29, thus allowing the stopper 24 to move toward the first rockerarm 7 under the resiliency of the spring 25 until the piston 23 abutsagainst the step 27. In this condition, the mutually contacting ends ofthe piston 23 and the stopper 24 of the first coupling 21 are alignedwith the adjacent, mutually sliding side walls of the first and secondrocker arms 7, 8, and the mutually contacting ends of the piston 23 andthe stopper 24 of the second coupling 22 are aligned with the adjacent,mutually sliding side walls of the first and third rocker arms 7, 9.Thus, the first, second, and third rocker arms 7, 8, 9 are held inmutually side-by-side sliding contact for relative angular movement.

With the first through third rocker arms 7, 8, 9 being thusdisconnected, the second and third rocker arms, 8, 9 are not affected bythe angular movement of the first rocker arm 7. The second rocker arm 8is angularly moved in sliding contact with the first low-speed cam 4,whereas the third rocker arm 9 is angularly moved in sliding contactwith the second low-speed cam 5. Therefore, the intake valve 1a isalternately opened and closed by the second rocker arm 8, and the otherintake valve 1b is alternately opened and closed by the third rocker arm9. Any frictional loss of the valve operating mechanism is relativelylow because the first rocker arm 7 is held in sliding contact with thehigh-speed cam 5 under the relatively small resilient force of thelifter spring 20.

During low-speed operation of the engine, therefore, the intake valve 1ais alternately opened and closed at the valve timing and valve liftaccording to the profile of the first low-speed cam 3, whereas the otherintake valve 1b is alternately opened and closed at the valve timing andvalve lift according to the profile of the second and low-speed cam 4.Accordingly, the air-fuel mixture flows into the combustion chamber at arate suitable for the low-speed operation of the engine, therebyresulting in stable fuel combustion, improved fuel economy, stablelow-speed operation, and prevention of knocking. Since the profiles ofthe low-speed cams 3, 4 are different, the turbulence of the air-fuelmixture in the combustion chamber is increased for improved fueleconomy.

For medium-speed operation of the engine, the first and second rockerarms 7, 8 are interconnected by the first coupling 21, with the firstand third rocker arms 7, 9 remaining disconnected from each other, asshown in FIG. 5. More specifically, the hydraulic pressure chamber 29 ofthe first coupling 21 is supplied with hydraulic pressure from thehydraulic pressure from the hydraulic pressure passage 32 to cause thepiston 23 to push the stopper 24 into the second guide hole 35 againstthe resiliency of the spring 25 until the stopper 24 engages the step36. The first and second rocker arms 7, 8 are now prevented fromrelative angular movement, but, instead, are caused to swing in unison.

Therefore, the intake valve 1a is alternately opened and closed at thevalve timing and valve lift according to the profile of the high-speedcam 5, whereas the other intake valve 1b is alternately opened andclosed at the valve timing ad valve lift according to the profile of thesecond low-speed cam 4. The air-fuel mixture now flows into thecombustion chamber at a rate suitable for the medium-speed operation ofthe engine, resulting in a relatively high charging efficiency andgreater turbulence of the air-fuel mixture in the combustion chamber andhence an improved fuel economy, as with the low-speed operation.

When the engine is to operate at a high speed, the first and thirdrocker arms 7, 9 are interconnected by the second coupling 22, as shownin FIG. 6, by supplying hydraulic pressure into the hydraulic pressurechamber 29 of the second coupling 22. Inasmuch as the first and secondrocker arms 7, 8 remain connected by the first coupling 21 at this time,the rocker arms 7, 8, 9 are caused to swing by the high-speed cam 5. Asa consequence, the intake valves 1a, 1b are alternately opened andclosed at the valve timing and valve lift according to the profile ofthe high-speed cam 5. The charging efficiency is increased to enable theengine to produce high output power and torque.

The inner space of the rocker shaft 6 is divided into the hydraulicpressure supply passages 32, 33 by the axially extending partition 31,and the hydraulic pressure supply passages 32, 33, are held incommunication with the hydraulic pressure chambers 29 of the respectivefirst and second couplings 21, 22. Therefore, the hydraulic pressure canbe supplied from one axial end of the rocker shaft 6, thereby making thehydraulic pressure supply circuit simple in a valve operating device ina multicylinder internal combustion engine.

As a modification of the first embodiment, the first and third rockerarms 7, 9 may be interconnected, while the first and second rocker arms7, 8 are disconnected during the medium-speed operation of the engine.With such an arrangement, the intake valve 1a is alternately opened andclosed at the valve timing and valve lift according to the profile ofthe first low-speed cam 3, whereas the other intake valve 1b isalternately opened and closed at the valve timing and valve liftaccording to the profile of the high-speed cam 5.

FIG. 7 shows a second embodiment of the present invention. In thisembodiment a piston 23' is slidably disposed in each of the second andthird rocker arms 8, 9, and stoppers 24' are slidably disposed in thefirst rocker arm 7 for urging stoppers 24 toward the pistons 23'. Thesecond and third rocker arms 8, 9 have hydraulic passages 34, 42providing communication between the hydraulic pressure supply passages32, 33 and the hydraulic pressure chambers 29 of the selective couplings21', 22'.

In addition to the advantages of the first embodiment, in thisembodiment any malfunctions due to hydraulic pressure leakage can beprevented with the hydraulic pressure chambers 29 being provided in thesecond and third rocker arms 8, 9.

FIG. 8 illustrates a third embodiment in which the first coupling 21 isdisposed between the first and second rocker arms 7, 8, and the secondcoupling 22' is disposed between the first and third rocker arms 7, 9.The third embodiment is as advantageous as the second embodiment.

According to a fourth embodiment shown in FIG. 9, the first and secondlow-speed cams 3, 4 of the first embodiment are replaced with circularraised portions 64, 65 integrally formed on the camshaft 2.

The arrangement of FIG. 9 may be employed in combination with a certaincylinder of a multicylinder internal combustion engine. In a low-speedrange, due to the presence of the circular raised portions 64, 65, bothof the intake valve 1a, 1b are kept at rest, thereby disabling thecylinder for highly improved fuel economy. In a medium-speed range, onlyone of the intake valves 1a is operated to increase engine output power.In a high-speed range, both of the intake valves 1a, 1b are operated forhigher engine output power.

FIG. 10 illustrates a fifth embodiment of the present invention. In thisembodiment, the second and third rocker arms 8', 9' are held against theintake valves 1a, 1b, respectively, through hydraulic tappets T1, T2.The rocker shaft 6 has therein an axially extending partition 45 of aY-shaped cross section forced or fixedly mounted therein or integrallyformed therewith. The partition 45 divides the inner space of the rockershaft 6 into three parallel hydraulic pressure supply passages 46, 47,48.

The second and third rocker arms 8', 9' have respective hydraulicpassages 49 for supplying hydraulic pressure to the respective hydraulictappets T1, T2. The rocker shaft 6 has a hole 50 defined therein forproviding communication between the hydraulic passages 49 and thehydraulic pressure supply passages 46. A rocker arm (not shown) disposedbetween the second and third rocker arms 8', 9' has annular grooves 51,52 surrounding the rocker shaft 6 in a position corresponding to thecouplings 21, 22 and also has hydraulic passages 55, 56 through whichthe hydraulic pressure chambers of the couplings 21, 22 communicaterespectively with the annular grooves 51, 52. The rocker shaft 6 alsohas a hole 53 communicating between the hydraulic pressure supplypassage 47 and the annular groove 51 and a hole 54 communicating betweenthe hydraulic pressure supply passage 48 and the annular groove 52.

According to the fifth embodiment, each of the hydraulic tappets T1, T2,the coupling 21, and the coupling 22 can individually be supplied withhydraulic pressure, and the hydraulic pressure circuit is notcomplicated.

FIG. 11 shows a sixth embodiment of the present invention. In thisembodiment, the rocker shaft 6 has an axially extending partition 60 ofan X-shaped cross section forced or fixedly mounted therein orintegrally formed therewith. The partition 60 divides the inner space ofthe rocker shaft 6 into four parallel hydraulic pressure supplypassages, 46, 47, 48, 59. As with the fifth embodiment, the hydraulicpressure supply passages 46, 47, 48 communicate with the respectivehydraulic pressure chambers of the hydraulic tappets T1, T2, and withthe couplings 21, 22. The hydraulic pressure supply passage 59communicates with a hydraulic passage 58 for supplying lubricating oilto the cam slippers and a separate hydraulic passage (not shown) forsupplying lubricating oil to the cam journals. For this purpose, a hole57 defined in the rocker shaft 6 is caused to connect annular grooves 61defined in the respective rocker arms 7, 8', 9' with the hydraulicpressure supply passage 59.

In addition to the advantages of the fifth embodiment, the sixthembodiment has an additional advantage in that lubricating oil can besupplied to the slidingly contacting surfaces of the cams 3, 4, 5, tothe rocker arms 7, 8', 9' and also to the cam journals through a simplehydraulic passage arrangement.

In FIGS. 12 and 13 which show another embodiment of the presentinvention, a pair of intake valves V1, V2 are disposed in an engine body101, and can be opened and closed by a cam C integrally formed on acamshaft 102 rotatable in synchronism with rotation of the engine at aspeed ratio of 1/2 with respect to the speed of rotation of the engine,and also by first and second rocker arms 103, 104, angularly movableabout an axis parallel to the camshaft 102, and a selectively actuatedcoupling 105 disposed in the rocker arms 103, 104. The intake valves V1,V2 are operated selectively in a mode in which both are opened andclosed, or a mode in which only intake valve V1 is opened and closed.The engine body 101 also has a pair of exhaust valves (not shown) whichcan be opened and closed in a manner similar to the intake valves V1,V2.

The camshaft 102 is rotatably disposed above the engine body 101. Thecam C is integrally formed with the camshaft 102 in alignment with theintake valve V1. The camshaft 102 has an integral concentric surface ofthe raised portion 106 aligned with the other intake valve V2. Thesurface of the raised portion 106 is a circle having a radius equal tothe radius of the base circle 107 of the cam C. The first rocker arm 103has an integral cam slipper 108 positioned on its upper surface and heldin sliding contact with the cam C, and the second rocker arm 104 has anintegral slipper 109 positioned on its upper surface and held in slidingcontact with the raised portion 106.

The rocker arms 103, 104 have base portions angularly movably supportedon a rocker shaft 110 fixed to the engine body 101 parallel to thecamshaft 102, the base portions being in sliding contact with eachother.

The rocker arms 103, 104 have on each of their ends housings 111, 112,respectively for engaging the upper ends of the respective intake valvesV1, V2. Hydraulic lash adjusters T1, T2 are disposed in the respectivehousings 111, 112. The hydraulic lash adjusters T1, T2 are basically ofthe same construction. Accordingly, the structure of only one of thehydraulic lash adjusters, that indicated as T2, will be described indetail.

The hydraulic lash adjuster T2 has a hydraulic pressure chamber 115defined in the rear side of a plunger 114 which is normally urged by aspring 113 to move into engagement with the intake valve V2. A checkvalve in the form of a ball 117 is interposed between the hydraulicpressure chamber 115 and a hydraulic reservoir chamber 116 communicatingwith a hydraulic supply source (not shown) at all times.

The housing 112 has a bore 118 opening toward the intake valve V2. Theplunger 114, which is closed at its lower end, is slidably disposedwithin the bore 118. The closed lower end of the plunger 114 contains aspherical head 119 directed toward the intake valve V2. A ring 120 isheld against the inner surface of the open end of the bore 118 forpreventing the plunger 114 from being displaced therefrom.

The hydraulic reservoir chamber 116 is defined by a cylindrical member121 slidably fitted in the plunger 114. The hydraulic pressure chamber115 is defined between the lower end of the cylindrical member 121 andthe lower end of the plunger 114. A valve cage 122 is disposed in thehydraulic pressure chamber 115 and pressed against the cylindricalmember 121 by a spring 113. The spherical check valve 117 is floatinglyhoused in the valve cage 122. The cylindrical member 121 has a valvehole 123 defined in the lower end thereof and communicating with thehydraulic pressure chamber 115. The communication between the valve hole123 and the hydraulic pressure chamber 115 can be closed by the checkvalve 117.

The cylindrical member 121 has an annular groove 124 provided in itsouter surface that communicates via a passage 124' with the hydraulicreservoir chamber 116. The plunger 114 has an annular groove 125 definedin its outer surface that communicates with the annular groove 24 viapassage 25' irrespective of relative movement of the cylindrical member21 and the plunger 14. The cylindrical member 21 is biased upwardly bythe force of the spring 113 to be pressed against the closed end of thebore 118. The upper end of the cylindrical member 121 has through-hole126 communicating with the hydraulic reservoir member chamber 16. Thebore 118, the plunger 114, and the cylindrical member 121 cooperate attheir upper ends to define an annular chamber 127. A vent hole 128extending through the second rocker arm 104 vents the annular chamber127 to atmosphere in order to prevent the plunger 114 from moving due topressurization and pressure reduction in the annular chamber 127.

The rocker shaft 110 has an axially extending partition 136 forced orfixedly mounted therein, or integrally formed therewith. The partition136 divides the interior of the rocker shaft 110 into first and secondhydraulic pressure supply passages 137, 138. The first and secondhydraulic pressure supply passages 137, 138 are individually connectedto corresponding hydraulic pressure supply sources (not shown). Thefirst hydraulic pressure supply passage 138 is supplied with a fluid ofrelatively high hydraulic pressure.

The second rocker arm 104 has an annular groove 139 surrounding therocker shaft 110. A hole 140 is provided in the rocker shaft 110 throughwhich the first hydraulic pressure supply passage 37 communicates withthe annular groove 139. The second rocker arm 104 has a first hydraulicpassage 131 interconnecting the annular groove 139 and the annulargroove 125 of the plunger 114, the first hydraulic passage 131 having arestriction 132. Thus, the hydraulic reservoir chamber 116 of thehydraulic lash adjuster T2 is held in communication with the firsthydraulic pressure supply passage 137 at all times. The restriction 132serves to limit the rate of supply of the hydraulic medium from thefirst hydraulic pressure supply passage 137. The housing 112 of thesecond rocker arm 104 has a restriction 133 in its upper portioncommunicating with the through-hole 126. This restriction 133 serves tolimit the rate of discharge of the hydraulic medium from the hydraulicreservoir chamber 116. The restrictions 132, 133, therefore, prevent thehydraulic pressure in the hydraulic reservoir chamber 116 from beingabruptly varied.

As shown in FIG. 14, which is provided with a lash adjuster such as thatdescribed above in connection with the second rocker arm 104, the firstrocker arm 103 has an annular groove 142 communicating with the firsthydraulic pressure supply passage 137 and a first hydraulic passage 142connecting the hydraulic lash adjuster T1 and the annular groove 141.The first hydraulic passage 142 has a restriction (not shown) similar tothe restriction 132 in passage 131.

Flanges 134, 135 are mounted on the upper portions of the respectiveintake valves V1, V2. The intake valves V1, V2, are normally urgedupwardly in a valve closing direction by valve springs S1, S2 (FIG. 13)disposed between the flanges 134, 135 and the engine body 101 around theintake valves V1, V2, respectively.

The first and second rocker arms 103, 104 are held in lateral slidingcontact with each other. A selectively actuated coupling 105 is arrangedin the rocker arms 103, 104 for selectively disconnecting the rockerarms for relative angular displacement and interconnecting them formovement in unison.

The coupling 105 includes a piston 151 movable along an axis parallel tothe rocket shaft 110 between a position in which it interconnects thefirst and second rocker arms 103, 104 and a position in which itdisconnects the rocker arms from each other. Also provided are a stopper152 for limiting the movement of the piston 151, and a spring 153 forurging the stopper 152 to move the piston 151 toward the position todisconnect the rocker arms from each other.

The first rocker arm 103 has a first guide hole 154 opening toward thesecond rocker arm 104 and extending parallel to the rocker shaft 110.The first rocker arm 103 also has a smaller-diameter hole 156 near theclosed end of the first guide hole 154, with a step 155 being definedbetween the smaller-diameter hole 156 and the first guide hole 154. Thepiston 151 is slidably fitted in the first guide hole 154. The piston151 and the closed end of the smaller-diameter hole 156 cooperate todefine therebetween a hydraulic pressure chamber 157. The first rockerarm 103 also has a second hydraulic passage 158 communicating with thehydraulic pressure supply passage 138 in the rocker shaft 110 may meansof a through-hole 159 defined in the side wall of the rocker shaft 110.

The piston 151 has an axial length such that when its inner end abutsagainst the step 155, the other end thereof does not project from theside of the first rocker arm 103 facing the second rocker arm 104.

The second rocker arm 104 has a second guide hole 160 opening toward thefirst rocker arm 103 for registration with the first guide hole 154 inthe first rocker arm 103, the second guide hole 160 having the samediameter as that of the first guide hole 154. The circular stopper 152is slidably fitted in the second guide hole 160. The second rocker arm104 also has a smaller-diameter hole 162 near the closed end of thesecond guide hole 160, with a step 161 defined between the second guidehole 160 and the smaller-diameter hole 162 for limiting movement of thecircular stopper 152. The second rocker arm 104 also has a through-hole163 defined coaxially with the smaller-diameter hole 162 and smaller indiameter than the hole 162, the hole 163 extending between the bottom ofthe hole 162 and the outer side of the second rocker arm 104. A guiderod 164 jointed integrally and coaxially to the circular stopper 152,extends through the hole 163. The coil spring 153 is disposed around theguide rod 164 between the stopper 152 and the closed end of thesmaller-diameter hole 162.

The first and second guide holes 154, 160 are aligned coaxially witheach other when the cam slipper 108 of the first rocker arm 103slidingly contacts the base circle 107 of the cam C and the slipper ofthe second rocker arm 104 slidingly contacts the circular raised portion106.

Operation of the above embodiment is as follows. During low-speedoperation of the engine, no working oil is supplied to the hydraulicpressure chamber 157 of the coupling 105. The stopper 152 is biased bythe spring 153 toward the first rocker arm 103, and the piston 151 abutsagainst the step 155. Under this condition, the abutting surfaces of thepiston 151 and the stopper 152 are aligned with the sliding surfaces ofthe first and second rocker arms 103, 104. Therefore, the first andsecond rocker arms 103, 104 are disposed in sliding contact with eachother for relative angular displacement, while the piston 151 and thestopper 152 are in sliding contact with each other.

When the first and second rocker arms 103, 104 are thus disconnected bythe coupling 105, the first rocker arm 103 is angularly moved by the camC to cause the intake valve V1 to be opened and closed at the timing andlift according to the cam profile of the cam C. The slipper 109 of thesecond rocker arm 104 remains in sliding contact with the circularraised portion 106, thereby keeping the other intake valve V2 closed.

For high-speed operation of the engine, working oil under a relativelyhigh pressure is supplied from hydraulic supply passage 38 to thehydraulic pressure chamber 157 of the coupling 105. The piston 151 isthereby moved into the second guide hole 160, while compressing thespring 153 until the stopper 152 abuts against the step 161, whereuponthe first and second rocker arms 103, 104 are interconnected by thepiston 151. With the first and second rocker arms 103, 104 thusconnected to each other, they are angularly moved together as the cam Crotates, thereby opening and closing the intake valve V1, V2 in unison.

When the intake valves V1, V2 are closed at the time the coupling 105connects the rocker arms 103, 104, the first rocker arm 103 is urged byhydraulic lash adjuster T1 in a direction to bring the cam slipper 103into sliding contact with the base circle 107 of the cam C, and thesecond rocker arm 104 is urged by the hydraulic lash adjuster T2 in adirection to bring the slipper 109 into sliding contact with the raisedportion 106. Therefore, since the first and second guide holes 154, 160are axially aligned with each other, the pin 151 can move smoothly forallowing reliable interconnection of the rocker arms by the coupling105.

By means of the arrangement, the hydraulic lash adjusters T1, T2 aresupplied with a relatively low hydraulic pressure, and the coupling 10is supplied with a relatively high hydraulic pressure. The hydrauliclash adjusters T1, T2 and the coupling 105 can, therefore, each beoperated under suitable hydraulic pressures that can differ from oneanother.

FIG. 15 shows another embodiment of the present invention. In thisembodiment, the coupling 105 is disposed across a first hydraulicpassage 142' by which the hydraulic lash adjuster T1 of the first rockerarm 103 and the first hydraulic pressure supply passage 137 areconnected. The first rocker arm 103 has an annular groove 165 whichsurrounds the piston 151 of the coupling 105 at all times. The firsthydraulic passage 142' communicates with the annular groove 154 therebyestablishing fluid communication between the passage 142' and thehydraulic supply passage 173 via the hole 140' in the rocker shaft 110and the groove 151 in the rocker arm 103.

FIG. 16 illustrates yet another embodiment of the present invention. Inthis embodiment first and second rocker arms 103, 104 are angularlymovably supported at their intermediate portions on the rocker shaft110. Hydraulic lash adjusters T1, T2 engaging the intake valves V1, V2,respectively, are disposed in ends of the respective rocker arms 103,104. A cam slipper 108 is defined on the lower portion of the oppositeend of the first rocker arm 103 and held in sliding contact with the camC, and a slipper 9 is similarly defined on the lower portion of theopposite end of the second rocker arm 104 and held in sliding contactwith the circular raised portion 106. The selectively actuated coupling105 is disposed in the rocker arms 103, 104 in a position displaced fromthe rocker shaft 110 toward the opposite ends of the rocker arms.

The rocker shaft 110 has its second hydraulic pressure supply passage138 connecting with the coupling 105 and its first hydraulic pressuresupply passage 137 connecting with the hydraulic lash adjusters, T1, T1,the first and second hydraulic pressure supply passages, 37, 38, beingdefined on opposite sides of the partition 136. The second hydraulicpressure passage 138 and the coupling 104 are interconnected by a secondhydraulic passage 158, and the hydraulic lash adjusters T1, T2, and thefirst hydraulic passages 142, 131.

In the embodiment of the invention illustrated in FIG. 17, the coupling105 is disposed in the first and second rocker arms 103, 104 in aposition displaced from the rocker shaft 110 toward the hydraulic lashadjusters T1, T2.

Annular grooves 141, 139 communicating with the first hydraulic pressuresupply passage 137 are defined in the first and second rocker arms, 103,104 respectively, in surrounding relation to the rocker shaft 110. Thehydraulic lash adjusters T1, T2, and the annular grooves 141, 139, areconnected by the individual first hydraulic passages 142, 131. Thecoupling 105 is fluidly connected to the second hydraulic pressuresupply passage 138 via the second hydraulic passage 158.

In the embodiment of the invention illustrated in FIG. 18 a hydrauliclash adjuster T is mounted on the rocker arm 103. The rocker arm 103,which is swingably driven by the cam C, is engaged by a single intakevalve V. The selectively actuated coupling 105 is disposed between therocker arm 103 and a separate rocker arm 104 that is held in slidingcontact with the circular raised portion 106 on the camshaft 2. Therocker arm 103 has a first hydraulic passage (not shown) leading to thehydraulic lash adjuster T and a second hydraulic passage (not shown)leading to the selective coupling 105.

In the embodiment of the invention illustrated in FIG. 19, one of a pairof rocker arms 103, 104, between which a selectively actuated coupling105 is disposed, e.g., the rocker arm 104, is bifurcated to form twoarms 104a, 104b, each of which has hydraulic lash adjusters (not shown)that each engage one of a pair of intake valves (not shown),respectively. The rocker arm 104 has a first hydraulic passage 131defined therein across the coupling 105, and the arms 104a, 104b haverespective second hydraulic passages 131a, 131b, connecting the firsthydraulic passage 131 and the respective hydraulic lash adjusters. Theother rocker arm 103 has a hydraulic passage 158 leading to the coupling105.

In the embodiment of FIG. 20, hydraulic lash adjusters (not shown)engaging respective intake valves (also not shown) are mountedrespectively on rocker arms 171, 172, that are swingable in slidingcontact with respective cams (not shown). A rocker arm 173 is disposedbetween the rocker arms 171, 172 and held in sliding contact with acircular raise portion, similar to the previously described raisedportion 106 on the camshaft. Selectively actuated couplings 105' aredisposed between the rocker arms 171 173 and between the rocker arms172, 173, respectively.

The rocker arms 171, 172 have first hydraulic passages 174, 175,respectively, interconnecting the hydraulic lash adjusters and a firsthydraulic pressure supply passage 177. The passages 174, 175 each extendacross the couplings 105'. The rocker arms 173 has a pair of secondhydraulic passage 176 by means of which the couplings 105' are connectedto the second hydraulic pressure supply passage 138.

In the embodiment of FIG. 21, the rocker arm 171 has a first hydraulicpassage 174; the rocker arm 172 has first and second hydraulic passages175, 176; and rocker arm 173 has a second hydraulic passage 177.

According to the present invention, therefore, selectively actuatedcouplings are disposed between mutually adjacent rocker arms forinterconnecting and disconnecting them. The couplings are operableindependently of each other by receiving operating fluid from separatesources of hydraulic pressure. Therefore, the entire operation range ofan engine can be divided into three or more ranges for valve operationcontrol to achieve increased engine output power and fuel economy.Moreover, as shown in the several described embodiments of theinvention, first and second hydraulic passages can be provided for anynumber of valves and any particular arrangement of rocker arms andselectively actuated couplings, which may vary from control mode tocontrol mode. Two second hydraulic passages can independently beprovided in order to allow three-mode control.

Since a plurality of hydraulic pressure passages communicatingseparately with the respective selective couplings are defined by anaxially extending partition in the rocker shaft, the hydraulic pressuresupply system, even one used in a multicylinder internal combustionengine, can be simplified. Additionally, the number of separatehydraulic pressure passages can be selected so as to additionallyprovide operating fluid to hydraulic lash adjusters and oil to lubricatethe operating parts of the apparatus.

While the present invention has been described with respect to intakevalve in the aforesaid embodiments, it will be appreciated that theinvention is equally applicable to the operation of exhaust valves. Itis also possible to change cylinder cut-off operation and variable valvetiming in a plurality of modes with a single intake or exhaust valve,without any limitation on the control modes and the number of valves.Therefore, it should be understood that, although preferred embodimentsof the invention have been illustrated and described herein, changes canbe made in the described arrangements without departing from the scopeof the appended claims.

I claim:
 1. For use in an internal combustion engine having a cylinder,intake and exhaust valves operable in said cylinder, selective valveoperating means, comprising:a plurality of pivotally mounted rocker armsincluding at least one driver rocker arm having an end operablyconnecting .Iadd.one of .Iaddend.said valves and a free rocker armselectively connectable with an adjacent driver rocker arm; a camshaftrotatably driven by said engine; a plurality of cams mounted forrotation on said engine, each said cam engaging a follower surface oneach said rocker arm; hydraulically operated, selectively actuablecoupling means carried by respective of said rocker arms for selectivelyconnecting or disconnecting adjacent rocker arms; fluid passages in saidrocker arms for supplying operating fluid to said coupling means; andmeans for supplying operating fluid independently to each said fluidpassage, including: a rocker shaft having an axial opening mounting saidrocker arms for pivotal movement; partition means in said rocker shaftopening defining a plurality of independent fluid supplies; and meansfor independently connecting respective of said fluid supply lines torespective of said rocker arm passages.
 2. The apparatus according toclaim 1 including a hydraulic lash adjuster operably connecting eachsaid driver rocker arm to the associated valve; fluid supply passagesthrough said driver rocker arms connecting with said lash adjusters; andmeans for connecting one said rocker shaft fluid supply line to saidrocker arm lash adjuster fluid supply passages.
 3. The apparatusaccording to claim 1 including lubricating fluid supply passages in saidrocker arms for conducting lubricating oil to said follower surfacethereon; and means for connecting said lubricating fluid supply passagesto one of said rocker shaft fluid supply lines.
 4. The apparatusaccording to claim 1 in which said rocker arms include a free rocker arminterposed between a pair of driver rocker arms, said coupling meansincluding independent couplers for selectively connecting said freerocker arm to each adjacent driver rocker arm, and means forindependently connecting the fluid passages in said rocker arms betweenrespective of said rocker shaft supply lines and each said coupler 5.The apparatus according to claim 4 in which said coupling meanscomprises a pair of couplers oppositely disposed in said free rocker armfor selective connection with and adjacent driver rocker arm.
 6. Theapparatus according to claim 4 in which said coupling means comprises acoupler in each said driver rocker arm for selective connection withsaid free rocker arm.
 7. The apparatus according to claim 2 in whichsaid rocker arms include a free rocker arm interposed between a pair ofdriver rocker arms; said coupling means including separate couplers forselectively connecting said free rocker arm to the adjacent driverrocker arm; said rocker arm fluid passage including first passagesconnecting with said couplers and second passages connecting with saidlash adjusters; and means for connecting said first and second passageto respective of said rocker shaft supply lines.
 8. The apparatusaccording to claim 2 including a driver rocker arm having a bifurcatebody operably connecting a pair of valves; a lash adjuster on eachsegment of said body; and said fluid supply passage through said driverrocker arm being coextensive with said segments.
 9. The apparatusaccording to claim 2 in which said rocker shaft is disposed between saidrocker arm end and said follower surface; said coupling means beingdisposed adjacent said follower surface; said coupling means fluidsupply passages and said lash adjuster fluid supply passages extendingoppositely from said rocker shaft.
 10. The apparatus according to claim1 including a rocker arm having a rocker base fixed to said rockershaft; and annular groove in said rocker base communicating with saidrocker arm passage; and means for communicating said annular groove withone of said rocker shaft fluid supply lines.
 11. The apparatus accordingto claim 1 in which said rocker shaft is disposed between said rockerarm end and said follower surface; said coupling means disposed adjacentsaid rocker arm end; said coupling mean fluid supply passages and saidlash adjuster fluid supply passages being arranged to connect one withsaid rocker shaft and one with said annular groove.
 12. The apparatusaccording to claim 2 in which said coupling means comprises guide holesin adjacent rocker arms having registrable openings; a movable positioncarried by one of said guide holes for extension into the opening in theadjacent guide hole; said coupling means fluid supply passagecommunicating with said one guide hole at the end remote from saidopening; an annular groove in the wall of said one guide hole adjacentthe opening therein; and said lash adjuster fluid supply passageintersecting said annular groove.
 13. The apparatus according to any oneof claims 1 to 3 in which said rocker shaft fluid supply lines conductfluids at different pressures.
 14. The apparatus according to any one ofclaims 1 to 12 in which each of said cams has a cam profile defining adifferent mode of valve operation and said coupling means beingselectively actuable in accordance with a desired mode of valveoperation.
 15. The apparatus according to claim 14 in which at least oneof said cams has a circular profile. .Iadd.
 16. For use in an internalcombustion engine having a cylinder, intake and exhaust valves operablein said cylinder, selective valve operating means comprising:a rockershaft having a hollow interior defining a fluid supply means; aplurality of rocker arms mounted for pivotal movement on said rockershaft, said rocker arms including at least one drive rocker arm havingan end operably connecting one of said valves; a camshaft rotatablydriven by said engine; cam means mounted for rotation on said camshaftand operably engaging the follower surface of selected rocker arms;hydraulically operated, selectively actuable coupling means carried bysaid rocker arms for selectively connecting or disconnecting adjacentrocker arms; a hydraulic lash adjuster operably connecting said driverrocker arm to its associated valve; fluid supply passages through saidrocker arms communicating at one end with said fluid supply means insaid rocker shaft and at the other end with said coupling means and saidlash adjuster, respectively; and lubricating fluid supply passages insaid rocker arms for conducting lubricating fluid to said followersurface; and means for connecting said lubricating fluid supply passagesto said fluid supply means. .Iaddend. .Iadd.
 17. For use in an internalcombustion engine having a cylinder, intake and exhaust valves operablein said cylinder, selective valve operating means comprising:a rockershaft having a hollow interior defining a fluid supply means; aplurality of rocker arms mounted for pivotal movement on said rockershaft, said rocker arms including at least one drive rocker arm havingan end operably connecting one of said valves; a camshaft rotatablydriven by said engine; cam means mounted for rotation on said camshaftand operably engaging the follower surface of selected rocker arms;hydraulically operated, selectively actuable coupling means carried bysaid rocker arms for selectively connecting or disconnecting adjacentrocker arms; a hydraulic lash adjuster operably connecting said driverrocker arm to its associated valve; fluid supply passages through saidrocker arms communicating at one end with said fluid supply means insaid rocker shaft and at the other end with said coupling means and saidlash adjuster, respectively; and wherein said rocker arms include a freerocker arm interposed between a pair of driver rocker arms and saidcoupling means including couplers for selectively connecting said freerocker arm to each adjacent drier rocker arm. .Iaddend. .Iadd.
 18. Foruse in an internal combustion engine having a cylinder, intake andexhaust valves operable in said cylinder, selective valve operatingmeans comprising:a rocker shaft having a hollow interior defining afluid supply means; a plurality of rocker arms mounted for pivotalmovement on said rocker shaft, said rocker arms including at least onedrive rocker arm having an end operably connecting one of said valves; acamshaft rotatably driven by said engine; cam means mounted for rotationon said camshaft and operably engaging the follower surface of selectedrocker arms; hydraulically operated, selectively actuable coupling meanscarried by said rocker arms for selectively connecting or disconnectingadjacent rocker arms; a hydraulic lash adjuster operably connecting saiddriver rocker arm to its associated valve; fluid supply passages throughsaid rocker arms communicating at one end with said fluid supply meansin said rocker shaft and at the other end with said coupling means andsaid lash adjuster, respectively; wherein said rocker arms include afree rocker arm interposed between a pair of driver rocker arms and saidcoupling means includes couplers for selectively connecting said freerocker arm to each adjacent driver rocker arm; and in which saidcoupling means comprises a pair of couplers oppositely disposed in saidfree rocker arm for selective connection with the adjacent driver rockerarms. .Iaddend. .Iadd.19. For use in an internal combustion enginehaving a cylinder, intake and exhaust valves operable in said cylinder,selective valve operating means comprising: a rocker shaft having ahollow interior defining a fluid supply means; a plurality of rockerarms mounted for pivotal movement on said rocker shaft, said rocker armsincluding at least one drive rocker arm having an end operablyconnecting one of said valves; a camshaft rotatably driven by saidengine; cam means mounted for rotation on said camshaft and operablyengaging the follower surface of selected rocker arms; hydraulicallyoperated selectively actuable coupling means carried by said rocker armsfor selectively connecting or disconnecting adjacent rocker arms; ahydraulic lash adjuster operably connecting said driver rocker arm toits associated valve; fluid supply passages through said rocker armscommunicating at one end with said fluid supply means in said rockershaft and at the other end with said coupling means and said lashadjuster, respectively; and wherein said lash adjuster is disposed onsaid rocker arm on the side of said rocker shaft opposite said followersurface. .Iaddend.